1. Field
Example embodiments relate to molecular devices and methods of manufacturing the molecular devices. Other example embodiments relate to molecular devices utilizing electric characteristics of functional molecules having functional groups, and methods of manufacturing the molecular devices.
2. Description of the Related Art
Technology for integrating semiconductor devices, which is based on Moore's Law, is continually being developed. However, there is a limit to the degree in which a semiconductor device (e.g., a transistor) can be integrated due to increased leakage current and/or heat loss that occurs as a result of an enlarged resistance of the semiconductor device. An increase in the leakage current and/or heat loss deteriorate the reliability of the semiconductor device.
Various solutions have been researched with regard to the development of a technology suitable for replacing conventional silicon technology. In large due to the recent development of nanotechnology, molecules having nano-sizes are used in an electronic device by a bottom-up method instead of a conventional top-down method in order to manufacture a molecule device, one of the smallest devices manufactured. A molecular device may have a higher integration degree, a higher response speed and/or be manufactured at a lower cost. A molecular device may be manufactured using molecular electronic technology.
Nanotechnology was developed in order to facilitate the manufacture of molecular devices in accordance with molecular electronic technology. The size of which a nano-electrode may be manufactured using current nanotechnology is limited to about 5 nanometers (nm), despite the use of an electron-beam lithography process. Because the size of a small molecule is about one nanometer, it is difficult to form a molecular junction between adjacent small molecules. The formation of a stable junction between the molecule and the electrode increases reproducibility of the process used to manufacture the molecular device. Recent research has been focused on methods to form a connection between adjacent electrodes separated by a distance substantially larger than the size of the molecule.
Conventional electrodes have problems such as an irregular spatial interval between adjacent electrodes and instability of a junction between the electrode and the molecules. It may be difficult to determine the number of molecules simultaneously connected to the electrodes.
Hereinafter, a conventional molecular device will be described with reference to the accompanying drawings.
FIG. 1A is a diagram illustrating a cross-sectional view of a conventional molecular device. FIG. 1B is diagram illustrating an enlarged cross-sectional view of portion “A” in FIG. 1A.
Referring to FIGS. 1A and 1B, nitride membranes 2 may be formed at both sides of a silicon substrate 1. One of the two nitride membranes 2 may be etched to form a hole 4 through the silicon substrate 1. A nano-hole 5 may be formed through the other of the two nitride membrane 2 by a reactive ion etching (RIE) process. Gold (Au) may be deposited in the hole 4 and the nano-hole 5 to form a lower electrode 6 in the hole 4 and the nano-hole 5.
A self-assembled monolayer 7 may be formed on the lower electrode 6. An upper electrode 10 may be formed on the self-assembled monolayer 7 and the nitride membrane 2. The upper electrode 10 may include a titanium (Ti) film 8 and a gold (Au) film 9. The titanium film 8 and the gold film 9 may be successively formed on the self-assembled monolayer 7 and the nitride membrane 2.
The above-described processes for manufacturing the conventional molecular device may be complicated. The molecular device may not have a desired integration degree due to taper etching processes used to form the hole 4 and the nano-hole 5. Yield and/or reliability of the conventional molecular device may be deteriorated. The self-assembled monolayer 7 of the conventional molecular device may be damaged while forming the upper electrode 10 on the self-assembled monolayer 7.